Ram jet propeller



June 28, 1960 c. A. SERRIADES RAM JET PROPELLER 2 Sheets-Sheet 1iZYVEHfUF CdlldfA/Vf/IVE A 5520,4256

Filed Nov. 28, 1955 June 28, 1960 c. A. SERRIADES 2,942,672

RAM JET PROPELLER United States Patent RAM JET PROPELLER Constantine A.Serriades, 732 Bittersweet Place, Chicago, 11].

Filed Nov. 28, 1955, Ser. No. 549,360

Claims. (Cl. 170-1354) This invention relates to an improved type of jetpropelled propeller structure. Specifically this invention relates to ajet propelled propeller structure having a twostage centrifugal flowcompressor integral with the propeller hub as a means for supplying anadditional velocity increment to air passing through the hollow bladeportions of the propeller structure.

In conventional propeller driven aircraft, the propeller and engine areseparate components in the thrust producing system for the aircraft.This independent unit type of construction has necessarily resulted in apower package of considerably great weight and bulk as compared to theweight of the propeller structure itself. The additional weight ofaccessories, control system, and a suitable gear reduction devicebetween the propeller structure and engine, accounted for a verysubstantial part of the non-pay load weight of the aircraft. It thusbecomes readily apparent that any proposed power system which couldintegrate the propeller and engine as a single structure would producesubstantial weight savings due to the elimination of many of theseparate drive and control components, necessary for the separatepropeller-engine type of construction.

Various integrated propeller-jet propulsion systems have been proposedfrom time to time as a solution to the problems above mentioned,- butfor the most part these systems have only been a combination of aconventional propeller and some form of separate jet propulsion device.A common example of this is the application of the ram jet engine to thetip of a propeller blade or rotor, such as is used in some experimentalhelicopters. Actually, most of the propeller-engine combinationscurrently in use are only a combination of a conventional propeller andjet engine, each unit retaining its individual form and function.

The present invention discloses an entirely novel form of integratedpropeller-jet propulsion system in which the propeller structure itselfbecomes part of a jet engine. By thus integrating the component partsand functions of the formerly separate jet engine and propeller,substantial advantages result in the form of a great reduction in weightof the combination structure, simplicity of construction andmaintenance, and an overall improvement in efliciency and control.

Briefly described, the present invention contemplates a generallyconventional propeller structure having two or more hollow blades havingan air inlet or series of inlets in the leading edge of one or more ofthe blade elements, substantially near the blade tip, and a jet exhaustoutlet or nozzle in the trailing edge of one or more of the bladeelements, serving to direct a jet exhaust out of the blade nozzletangential to the blade path, as a rotative power source for thepropeller.

The hollow hub portion of the propeller, in addition to retaining theblades in proper aerodynamic relationship and housing a pitch controldevice, also includes a twostage centrifugal flow compressor, receivingair from the inlet, or inlets, in one or more of the blades, therebysupplying an additional velocity increment to the air moving out of thesecond stage compressor toward the jet exhaust outlet in the rotativethrust producing blade. The compressor elements of the two-stagecentrifugal flow com; pressor are preferably of the double-entry,back-to-back type, the outlet of the first stage compressor elementfeeding the inlet or eye of the second stage compressor element, thougha single sided compressor blade cascade might be used in some particularinstallations. Air passing through the inlet and down the hollow bladetoward the hub, will thus receive an additional pressure and velocityincrement before passing through the jet exhaust outlet nozzle.

Provision is also made in the thrust producing blade element for theaddition, mixing and ignition of fuel, as an additional means ofaugmenting the jet velocity out of the jet nozzle in the thrust bladeelement. Furthermore, a substantial velocity increment is added to theair in the thrust producing blade element as it moves toward the jetexhaust outlet nozzle, due to the centrifugal force effects from therotation of the propeller assembly.

The provision for a two-stage centrifugal flow compressor in the hub ofthe propeller assembly also greatly extends the operating range andapplications of the present invention, in that a much lower propellerspeed can be maintained without danger of failure of the integral jetpropulsion system, due to the large velocity increment imparted to theair as it passes through the two-stage centrifugal flow compressor inthe hub of the propeller.

Thus it will be appreciated that the present invention discloses a noveltype of combined propeller and integrated jet propulsion system whichovercomes the disadvantages of excessive weight, bulk, control, andmaintenance problems, usually attributed to a separate component type ofconstruction, and at the same time presents an extremely versatile powerpackage for conventional propeller driven aircraft. I

In addition, the present invention is easily adaptable or usable, as asupplementary or secondary power source with a conventional engine,where a wide range of operatingspeeds and flight conditions areexpected. Use of the present invention in conjunction with aconventional engine would make possible a much smaller primary engineunit, the integral jet propulsion system of the present invention beingadequate to maintain normal flight and cruising speed once a desiredaltitude is reached. Substantial fuel savings could be expected whenusing the instant invention in conjunction with a conventional engine,particularly at high altitudes, where the jet propulsion system becomessubstantially more ellicient than a reciprocating engine.

The present invention will thusservefto increase the useful operatingrange, cruising speed, ceiling and generally add to the utility of -aconventional propeller driven aircraft when used as'a primary powersource or in conjunctionwith a conventional engine.

lt is an object then of the present invention to provide an improvedtype of propeller utilizing an integrated jet propulsion system as arotative power source,

Another object of the present invention is to provide an improvedjet-propelled propeller structure, in which a rotary type compressor isutilized to additionally pressurize air moving through the internalpassages of the propeller structure which form a jet flow passagethercthrough.

A further object of the present invention is to provide a method ofimparting an increased velocity increment to air moving through thehollow internal portions of a propeller blade, which forms a jetpropulsion flow passage, in addition to the velocity increase resultingfrom the centrifugal force of the blade rotation as the air moves towarda jet exhaust outlet in the blade tip.

a V 3 Anothefobject of the present invention is to'redu ce the'weight ofthe power=package of propeller "driven aircraft. 7 7

Yet another object of the present inventionis to provide'd anfimprovedtype of jetgpropelled propeller which overcomes the deficiencies*of theprior art where the-cen- ,g'inetype ofconstruction.

7 Many other obj ets and advantages of the present .in-

ventionwill Q become manifest te those '-versed in the art upon mal'ringreference :to the detailed description which follows and theaccompanying sheets of drawings. thedrawings: v a

Figure l a somewhat broken elevational view, par-r tiallysectionalanddiagrammatigwithsome parts omitted 'toshowjunderlyingparts; a

. Figure 2. is an enlarged fragmentaryview, partially sectional anddiagrammatic, illustrating the compressor assembly in the hub; and

Figure Bis-1a cross-sectional view, with parts in elevation, palongtheilineflIII-llL-of Figure 1.

As'shown on the drawings:

E'Intheembodiment "of the invention illustratedin' Figure :3

11, a 'threejbladedpropeller assembly is-shown, designated generallybythe, reference letter-P. V

* 'Thepropeller assembly P is comprised of-a hollowhub member 10, whichreceives a plurality of blades A, Band C. Theiblades A,B and Care'rotatablysecured itoithe hub'loso. as to permit a limited amount ofangular C. A series of baflies or agitators 23 are positioned in theaceeleratingexhaust passage l'lc-immediately-downstream of the main fuelinjector 21 to insure an adequate mixing of the fuel-air mixtureentering the combustion chamber 18. 7

It will thus be appreciated, that the blades A and B form the inlets,and that the blade C for-ms the exhaust outlet, for an integratedjet=propulsion system in the propeller assemblysl. 7

It should further be appreciated thatt while a three bladed propellerassembly-shown=in Figurel having two inlet blades and asin glie'exhaustblade, many variations in the number:and, .arrangen enttof inletrandexhaust outlets are possible depending on the application of theprincipal invention. 1

Referring now to Figure 2 in conjunction with Figure 1, a two-stagecentrifugal flow compressor assembly D a is enclosed in the hollowcentral portion of the hub memtheirfhub end withja centrifugalflowcompressor-'assemblyi D in the'hub 10, and at'their' blade tipjend witha pair-Voftangential,airihletSQ OpslZa andILZb'and a tang'entialijetexhaust out1eti13c, respectively.

7 QThe blades A, B and C ,also include1leading edge portionsi14a-c andtrailingedge portions 16a-,c. 'iThe air inlet 'scoopslza and 12b "arepositioned in the outer ,peripheryof itheblades A an'djB, in the leadingedge portionsll4a' and ,14b, respectively and serve-to turn ahighvelocity stream oftairlinto the radial, flow passageslla and 11b. A-plurality ofv fguide vanes 17a and 17b in the air"inlet's"12a and 12b,reduce the turbulence andienergy losses of theflh igh velocity airentering the.radial 'fiow passage 111a and 11b.

'jltrshouldbe appreciated that the radialfiow passages 'Iltz and 11b.are,soformed ;as tosminimize ductzlosses and the centrifugalforceefiects .on air in the passages .rr1oving .towardithe hub 10, due.to. therrotation of the ,ipropellertassembly-P.

"The" bladeQincludes theqietexhaust outlet13c in the Afflametholder :19,and spark gap, 20,-immediately up- ,stream of theicombustionrchaanberirmservewas a starting ,anfd mainfuelignitionmeans ion thejetcombustionproc essthe'eombustion chamberolii. .--A fuelinjectororspray 12, 1, substantially: upstream oftthe flame, holder 19 her 10. Thetwostage centrifugal flowieompressor assembly -D is comprised of apairof centrifugal rotors 26a and 26b, which-are in registry with thedecelerating radial flow passages 11a and 11b, respectively, and receive'initia'llypressurized'air therefrom. r

The'firs't-stage compressors 26a andi-26b =are*enclosed by a-pair'ofvolutes-27a and '27b,*the' compressors being preferably of the doubleentry type, 'but:it-should'-be understood that any other-type ofcompressor might be used depending on=the-particular--application oftheprincipal'invention. A pairpf difiuser rings ZSa and 25b surround thecompressors 26a and 26b respectively, and serve to initially impart avortex flowto high'velocity air leaving the-vanes of-the-compressors 26aand 26b. The volutes 27a-and 27b' -are-so formed as to divide thejairfiow moving-down thepassages-Jla and 11b toward'the hub '10, so as topermit an axial entry into 'theifirst-stage compressor rotors 26aand-26b. Internal guide'vanes, notshown, arealso provided in thevolutes27a and 27b *to minimize any losses around 'the compressor rotors 26aand 26b. t 7 The volutes 27a and-27bhave dilfuser' horns 28a and -28bztoprovidea pressurerecovery for high velocityair leaving the compressorswhich alternately communicate -with either eye of a asecond-stagecompressor rotor 29,

so as to form a two-stage compressor assembly.

The second stage compressor rotor 29 similar tothe first-stagecompressors 16a and-26b but is slightly. larger to accommodate .thedischarge offboth of the ljrst-stage -compressors when-'soperating atfulloutput. A diffuser ring '30 similar to the diffuser ringsigsizandjZSb, surrounds the -second stage compressor129 and also serves 'toinitially channel the fiowfr'romlthe coruprefifiotfi into a r unding-witer 31. .Arl ra ityp intern r ui vanes in the volume"31,-riot shown,also serve'to any duct losses. around the. compressor rotorjfl;

V diffuser m'3 ommun c te withth t ese sra ns *flo pa age c i t eb adeitan tprov de a pr ssur recovery for i elo y ai d scharg n t r t It .willthus be appreciated that ,the twostage com- 'p bly."Dimthe;hub mipr vidcia su s an ia velocity increase to air at jtheh ublil inthe.decelerating flow passagesdla and'llb, aboutto enterlheaccelerattseryes as the.niainQfuelsupplysource, and-receives,fuel'"connecting conduits'gzlin thesolidgportion f .theblade ing flow passage1 1c. 7

It will further;beappreciate rtha lthspr vi q tc th rstag comp ssemblylDis .only h w byw y ofrpre rr d ampl wh r th p qpe n meturej Pwil ;.be operated at comparatively; slow ,speeds. or under high 1 loadconditions,oan d that a propellerlstructure incorporating more, or lessthan ,a two-stage, three-compressor .ar- Ians ment, r sam other combi ioth r of m ht 'prove more advantageous for a particular installationdepending on the 7 application and ,operating conditions tconffimplated.a r j a ,,Aneathe pressur dth h vi 1Q ty-..ai haszenteredvth iaceleratingflcmpa as tl ai tth lbladekkarredetwquantity of fuel will bemetered into the flow from the fuel injector or spray 21. As the aircontinues to advance toward the blade tip, it will receive an additionalvelocity increase and mixing action due to the centrifugal force effectsof the blade rotation. The baffles or agitators 23 will further mix thefuel-air mixture until it is ignited by the spark gap 20. A flame front,established by the ignition from the spark gap will then ignite bleedfuel in the flame holder 19, which then acts as a continuous primaryignition source for the fuel-air mixture entering the combustion chamber18.

A plurality of cooling ducts or bleeds may be provided around thecombustion chamber 18, in the leading edge portion 14c in the eventconduction cooling to the atmosphere does not prove adequate.

Referring now to Figure 3, an enlarged cross-sectional view of the huband second-stage compressor is illustrated, in conjunction with thepropeller assembly accessorres.

In Figure 3, the second-stage compressor 29 is shown fastened to a shaft33 which is journalled for rotation at one end by a bushing 34 in thevolute chamber 28b and hub 10, and by a bearing assembly 36 at the otherend of the hub member 10. A planetary gear 37c is secured to the shaft33 and engages an internal sun gear 38 in the face of an accessorysupport member E, adjac'ent the hub 10. As the internal sun gear 38 isrigidly fastened to the accessory support member E, rotation of thepropeller structure P will induce a relative difierential rotation ofthe compressor rotor 29, thereby increasing the velocity increment ofair received from the volute chambers 28:: and 28b.

The first-stage compressors 26a and 26b, are similarly splined or keyedto a shaft and planetary gear which also engages the internal sun gear38 to provide a firststage compression for air entering the hub from thedecelerating passages 11a and 11b.

It will be appreciated that an optimum gear ratio is provided betweenthe internal sun gear 38 and planetary gears 37a-c so as to obtain theoptimum interstage compression ratio for a particular propeller assemblyand application.

The propeller assembly P is secured to a main shaft 39 by a series offasteners 40 and is rotatably journalled in the accessory support memberE by a plurality of bearing assemblies 41.

The main shaft 39 has a flanged portion 42 at its propeller hub endwhich includes an external ring gear 43. The ring gear 43 is in toothedengagement with a spur gear 44 which connects to a starter oraccumulator S,

through a shaft 46, to initially rotate the propeller structure P untilthe jet propulsion system becomes operable. Suitable clutch means, notshown, disengage the starter S when rotation of the propeller assemblybecomes selfsustaining.

An accessory drive gear 47 is secured to the main shaft 39 at its endopposite the hub member 10, by a plurality of fasteners 48. A fuel pumpF engages the accessory drive gear 47 through a shaft 49 and spur gear50. A generator or magneto G also engages the accessory drive gear 47through a shaft 51 and spur gear 52, to provide a high potential sparkto bridge the spark gap 20 in the blade C when starting the propellerassembly P.

The main shaft 39 is hollow and encloses a main fuel conduit 53, whichcommunicates fuel from the fuel pump F through the hub member 10 andblade C to the fuel injector or spray 21 and flameholder 19.

A high potential spark conduit 54 is concentrically positioned withinthe main fuel conduit 53 and communicates a high potential current fromthe generator G through the hub member 10 and blade C to the spark gap20.

It will thus be appreciated that the accessory support member Ecompactly houses the necessary accessories for the operation of theintegral jet propulsion system in the propeller assembly B so as topermit ease of maintenance, servicing or replacement, and at the sametime allowing greater space for a useful pay load.

It should further be appreciated that if the present invention wereutilized in conjunction with a conventional engine, as a supplementaryor stand-by power source, many of the accessories and controls shown inFig. 3 could be eliminated as they would be present in the primarypowersupply, thus making possible even greater weight savings andcompactness.

It will be understood that many other modifications and variations maybe efiected without departing from the scope of the novel concepts ofthe present invention.

1 claim as my invention:

l. A jet propelled propeller structure comprised of at least two hollowradial blades extending from a central hollow hub member andcircumferentially spaced with respect to one another, leading andtrailing edge portions on said blades, an air inlet in the leading edgeof at least one of said blades remote from said hub, a jet exhaustoutlet in the trailing edge of at least one other of said blades, acombustion chamber also in said trailing edge communicating with saidexhaust outlet, a radial flow inlet passage in the hollow internalportion of at least one of the blades registering with the inlet in saidblade, a radial flow outlet passage in the hollow internal portion of atleast one other of the blades registering with the jet exhaust outlet insaid blade, said radial flow inlet and outlet passages communicatingwith the hollow hub member, at least one first stage centrifugal flowcompressor in said hub member having an inlet and an outlet, at leastone second stage centrifugal flow oompressor in said hub memberhaving aninlet and an outlet in series with said first stage centrifugal flowoompressor, means communicating the inlet of said first stagecentrifugal flow compressorwith a radial flow inlet passage, meanscommunicating the outlet of said second stage centrifugal flowcompressor with a radial flow outlet passage,. means communicating theoutlet of said first stage centrifugal flow compressor with the inlet of'said second stage centrifugal flow compressor, means in said hub memberfor supplying fuel to air flowing through said radial flow outletpassage, and means for igniting said fuel to'produce a propulsionreaction in the combustion chamber and a jet exhaust out of said jetexhaust outlet thereby causing said propeller structure to rotate.

2. A jet propelled propeller structure comprised of a hollow central hubportion, a plurality of hollow radial blades extending from said centralhub portion having at least one tangential air inlet remote from saidhub portion and at least one tangential jet exhaust outlet in one ofsaid blades and forming a jet flow passage in another of said blades,said hollow blades forming a flow passage for air moving axially througheach of said blades toward the jet exhaust outlet and subjecting the airto the acceleration effects of the centrifugal force induced by therotation of said propeller structure, said central hub portion enclosinga two-stage centrifugal flow compressor system, at least one first stagecentrifugal flow compressor registering with a radial flow passage inone of the blades and receiving air therefrom, at least onesecond-stage, centrifugal flow compressor registering with a radial flowpassage and receiving initially compressed air from said first stagecentrifugal flow compressor, and fuel addition, mixing, means supplyingfuel to air flowing through said blades, and means for igniting saidfuel to increase the jet velocity of air moving tengentially out of saidjet exhaust outlet causing the propeller structure to rotate.

3. A jet propelled propeller structure comprising a plurality of hollowradial blade members extending from a central hub member and forming aradial jet flow passage therethrough spaced inwardly of the leading andtrailing edges of each of the blades, leading and

